Simulation of time-dependent behavior of backfills in jointed rocks by using a 3-D block-spring model

2001

A 3-D block-spring model (BSM3D) has been developed for simulating the behavior of jointed rocks. The model has been used to simulate the mining excavations in jointed rock masses around an open pit/underground setting. BSM3D has recently been modified to incorporate the time-dependent deformation of the paste materials in backfill process. The paper presents the fundamentals of BSM3D and its application in a caved mine to demonstrate the capability of the 3-D model. Backfilling is an effective approach to maintain the stability of rock masses around mining excavations. Paste backfill materials are becoming more popular due to the advantages of higher strength, smaller shrinkage and lower cost. To simulate the hardening process of the paste material and the time-dependent deformation, a special technique is adopted in BSM3D. A time factor is introduced in the procedure to simulate the variation of the paste material strength. At each time step, the contact states and failure conditions are examined between blocks. A new cycle of iteration is performed based on the new contact states and new material properties. The iteration process continues until the backfill properties are relatively stable. Then the displacements and stresses are calculated based on the contact forces between blocks.

Keywords: Backfill, time-dependent, Displacement, Stress, jointed rock, Numerical modelling, mining excavation